Replacing Render with UPVC cladding

matt1987

Hi All

Complete DIY beginner here..... I am looking to replace the rendering around the rear bay window with UPVC. On the face of it, it looks like a simple task (and to most people it probably is!) however I was just after some advice.

Most Youtube videos show the cladding being installed on timber batons - however I am unsure whats behind the rendering. I have attached some pictures as an example.

The bay runs at 90 degree angle which makes things slightly easier - however I am unsure as to whether I need to strip back the bay by taking away all the render and led flashing? Or can I just put the UPVC on top of this?

I have all the plastics - is there anything else in particular I need?

Thanks for looking!

Matt

FreeBear

You will find that the wall forming the upper part of the bay is of lightweight construction - Possibly a cement or lime render over laths and absolutely zero insulation behind. Stripping the lot back and fitting as much insulation as possible is advisable. I'd probably go for a Celotex/Kingspan type insulation board. Spacing the cladding away from the wall with battens is up to you, but do pay close attention to the finishing details - i.e. The junction with the brick wall, under the upper cill, and the drip line over the bottom window.

matt1987

FreeBear said:

You will find that the wall forming the upper part of the bay is of lightweight construction - Possibly a cement or lime render over laths and absolutely zero insulation behind. Stripping the lot back and fitting as much insulation as possible is advisable. I'd probably go for a Celotex/Kingspan type insulation board. Spacing the cladding away from the wall with battens is up to you, but do pay close attention to the finishing details - i.e. The junction with the brick wall, under the upper cill, and the drip line over the bottom window.

Thanks for your advice,

Basically I dont want the cladding to sit flush with the sill, because that could cause raise running from the sills to get in behind the cladding? 

So by stripping the whole lot back, taking of the led flashing and then installing insulation board, I could then in theory pin the cladding straight into the insulation board without using timber batons?

Regards

Matt

FreeBear

matt1987 said: So by stripping the whole lot back, taking of the led flashing and then installing insulation board, I could then in theory pin the cladding straight into the insulation board without using timber batons?

That is lead, not led - The latter is a light source.

You can not fix cladding directly on to insulation board. It needs to be nailed/screwed to something solid such as timber. If the wall is constructed how I suspect it is, there will be timber studs at 12"-14" centers. You can fix your cladding to these.

But before you do anything, get some qualified advice from a local expert - You may require vapour control membranes plus an air gap between cladding & insulation.

matt1987

Thanks - thats a great help!

Yes I did realise after you had pointed out that I was spelling lead incorrectly! Haha.

stuart45

Normally it's timber studs, OSB or ply sheathing, breather membrane, battens then cladding. 
The sheathing adds strength to the structure and prevents wind racking.

matt1987

stuart45 said:

Normally it's timber studs, OSB or ply sheathing, breather membrane, battens then cladding. 
The sheathing adds strength to the structure and prevents wind racking.

Thanks Stuart,

what mm OSB? Would this then negate the need for insulation or would you put the OSB then Insulation then Breather Membrane, batons and cladding? 

stuart45

Put the insulation between the studs, they are possibly 4x2's.
9mm OSB would probably be OK for the sheathing. The racking resistance depends on the nail spacing as well.
@travis-powers would be better placed to know the technical details better than me.

matt1987

Got you - 

So essentially

- Take off old render and flashing back to timber studs 

- place insulation between timber (30mm Cellotex?)

- OSB board over (pos 9mm)

- breathable membrane on

- timber batons running vertical (4x2’s?)

- On goes the cladding

I promise - I’ll be an expert by the time Iv done this! 😆

stuart45

You've almost got there. 
The studs are probably 4x2, so you can get much thicker Cellotex inbetween the studs.
For battens you only need 2x1's.

matt1987

Thanks again for your advice - really appreciate it.
If it goes well I’ll take a picture! Haha!